Researchers still know little about how cannabis may interact with various pharmaceutical medications and there are not enough studies.
Alcohol
Many patients use also alcohol and nicotine. There is a synergism effect with alcohol that causes THC to be absorbed more rapidly into the blood plasma of the user.
Alcohol combined with marijuana – makes both drugs stronger; manageable at low doses, but can cause vomiting, dizziness, and increased paranoia with large amounts of both.
Benzodiazepines
Both cannabis and benzodiazepine medications can have strong sedative effects on the brain, putting patients at risk of over sedation. Both compounds can have an effect on GABA, a calming neurotransmitter that dampens excitability in the brain.
Symptoms to watch for include:
Over sedation
Slowed or slurred speech
Slowed motor skills
Driving impairment
Cognitive impairment
Constipation
SSRIs
Cannabis may increase the effect of some SSRIs. Those with bipolar disorder should be careful since there is a risk for mood alterations when mixing these two types of medications. Both cannabis and SSRIs also increase serotonin. There is a potential risk developing sudden serotonin syndrome when combining these two drugs
Symptoms to watch for:
Difficulty sleeping
Symptoms of mania
Agitation
Anxiety
Excessive paranoia
Rapid heart rate
Headache
Gastrointestinal distress
Mood variability and mood swings
SNRIs
SNRIs treat nerve pain and depression. Both SNRIs and cannabis can cause serotonin fluctuations, which may make you more likely to develop sudden serotonin syndrome or have other unwanted mood side effects. Further, some cannabis compounds may increase blood concentrations of antidepressant drugs.
Anti-psychotic medications
There is some evidence to suggest that cannabis may heighten the effect of certain antipsychotic drugs, like Seroquel and Abilify.
warfarin
cannabis may increase warfarin anticoagulant effect by inhibiting its metabolism, and to a lesser extent, displacing warfarin from protein-binding sites. There is a danger for bleeding due to increased INR.
Pain killers
Buprenorphine, Methadone:
In high doses, this drug can also cause respiratory distress, coma, and death. When combined with cannabis, the risk of these things increases, since both substances depress the central nervous system. Both buprenorphine and cannabis are sedatives, which means the chance of being overly sedated with this combination is high.
Some symptoms to watch for include:
Excessive sedation
Respiratory problems
Difficulty controlling motor function
Slowed speech
Inability to perform cognitive tasks
Slowed or irregular heartbeat
Beta-blockers or other blood pressure medications:
Cannabis can cause blood pressure levels and heart rate to fluctuate, meaning that it might make some more sensitive to a heart attack. This is especially true for novice consumers. In regulars, cannabis may slow heart rate.
Some symptoms to watch for include:
Feeling faint, fainting
Dizziness
Nausea
